Cherry trees have thermic needs that must be satisfied in order to obtain profitable harvest. One of the most important factors to get a normal flower and vegetative budbreak is the chilling temperature exposition during the rest period. The amounts of “low” temperatures required to release cherry budbreak vary greatly among varieties. 'Bing’, ‘Van’ ‘EB’, ‘Ruby’, ‘Garnet’, ‘Marvin’, ‘Celeste’ and ‘Lapins’ cultivars were studied at two locations with different amount of chill unit (UF). They were calculated by Utah method. The heat units were calculated as Growing Degree Hours (GDH). The vegetative budbreak percentage increased whenever GDH or UF was bigger. But GDH only released budbreak when some minimum amount of UF (threshold) occurred. It was possible to differentiate some cultivars from chill requirements through comparison of mathematical regression model and also joined cultivars models that show a similar behavior.